I too would like some more information on this subject.It's been a few months since this thread started and it had no replies yet.

Personally I'd like to convert this bundle: https://github.com/masterzen/puppet-textmate-bundle, to add Puppet syntax highlighting support.Tried dragging and dropping the contents of the bundle inside a new directory. It shows up in the menu but when I load the syntax there's no highlighting whatsoever.

Basically, snippets can stay in a sub folder, everything else comes out into the root of the package. TM commands don't work in ST, so you'll have to either port them or lose them. See the following thread for a few more bits of info: